1. Field of the Invention:
This invention generally relates to circuit breakers and, more particularly, to a circuit breaker mechanism useful for remote power control for energy management, process control, motor, and lighting control.
2. Description of the Prior Art:
In recent years the cost of electric power has rapidly increased providing significant economic incentive to conserve energy. Concurrently, recent advances in electronic technology, and specifically minicomputer technology, have provided more sophisticated monitoring and control equipment which can be utilized to aid the energy conservation effort. One method of conserving electrical energy is to institute a control scheme which deenergizes specific electrical loads during preselected time periods. A very simple example of this conservation approach is to turn off office lights at a circuit breaker panel during non-working hours. This approach is used extensively, but has two inherent problems. First, the circuit breakers are not designed to function as on-off switches and secondly, manual operation is expensive and relatively inflexible.
These problems have been solved in the past by using a circuit breaker to provide fault protection and by adding a contactor in series with the breaker to function as the on-off switch. This traditional method solves the technical problems associated with the on-off operation since the circuit breaker mechanism (which is inherently limited to a moderate number of cycles) must operate only during fault conditions. The contactor, which is designed for cyclical duty, then performs the switching function. Contactors are traditionally supplied with solenoid actuators. These allow the switching function to be accomplished from a remote station, thereby increasing the flexibility of the system. The inherent disadvantage of this arrangement is the requirement for two costly items (circuit breaker and contactor) to perform the circuit protection and switching function.
In addition, these separate items require different mounting techniques and their installation requires cable routing that would not be required for a single device. The result of this additional complexity and cost has been to discourage the use of remotely operated energy management systems. The continued economic pressures to conserve electrical energy and the projected rapid growth in computerized energy management systems make the development of a remotely controlled magnet operated breaker timely.